Electrochromic polymer film, preparation method, electrochromic device comprising electrochromic polymer film, and application

Abstract

The present application provides an electrochromic polymer film, a preparation method, an electrochromic device comprising the electrochromic polymer film, and an application. The preparation method comprises: providing a precursor solution, wherein the precursor solution comprises a main solvent, an auxiliary solvent, an oxidizing agent, and a specific thiophene derivative monomer, the main solvent and the auxiliary solvent are different, and the auxiliary solvent can form a complex with at least some of metal ions in the oxidizing agent; and coating the surface of a substrate with the precursor solution, such that the thiophene derivative monomer undergoes an in-situ oxidative polymerization reaction to form an electrochromic polymer film.

Description

Electrochromic polymer films, preparation methods, electrochromic devices containing them, and applications Technical Field

[0001] This application relates to the field of electrochromic materials. Specifically, this application relates to an electrochromic polymer film, a preparation method thereof, an electrochromic device containing the same, and its applications. Background Technology

[0002] Electrochromic technology utilizes the stable and reversible color changes in a material's optical properties, such as reflectivity, transmittance, and absorptivity, under the influence of an applied electric field, thereby enabling active and dynamic control over light and solar radiation. This manifests as reversible changes in color and transparency. Currently, electrochromic technology is primarily used in the automotive, aircraft, glass curtain wall, and mobile phone industries, such as in car rearview mirrors, Boeing 787 aircraft, and mobile phone displays.

[0003] The traditional method for synthesizing electrochromic polymer films is electrochemical polymerization, but this method is both expensive and unsuitable for industrial production. Furthermore, this method requires a conductive substrate, and the film thickness is limited by the substrate's conductivity. Summary of the Invention

[0004] In view of the above-mentioned problems existing in the prior art, the first aspect of this application provides a method for preparing an electrochromic polymer film. The method includes: providing a precursor solution, wherein the precursor solution includes a main solvent, a secondary solvent, an oxidant, and a thiophene derivative monomer, wherein the main solvent and the secondary solvent are different, and the secondary solvent is capable of forming a complex with at least some of the metal ions in the oxidant; coating the precursor solution onto a substrate surface, causing the thiophene derivative monomer to undergo an in-situ oxidative polymerization reaction to form an electrochromic polymer film, wherein the thiophene derivative monomer includes one or more of the following organic compounds:

[0005] A second aspect of this application also provides an electrochromic polymer film, which comprises an organic material represented by the following structural formula:

[0006] n is 1 to 5, and / or it is prepared using the preparation method provided in this application.

[0007] A third aspect of this application also provides an electrochromic device, including an electrochromic layer comprising the electrochromic polymer film provided in this application; optionally, the transmittance of the electrochromic device varies by no less than 25% in the wavelength range of 590nm to 630nm and by no less than 10% in the wavelength range of 390nm to 450nm; optionally, the transmittance of the electrochromic device varies by no less than 20% in the wavelength range of 540nm to 560nm and by no less than 30% in the wavelength range of 660nm to 740nm; preferably, the electrochromic device includes a membrane switch, electronic paper, electronic price tag, electrochromic display, smart window, or vehicle head-up display.

[0008] The fourth aspect of this application also provides an application of the above-mentioned electrochromic polymer film in the field of electrochromism.

[0009] Beneficial effects: The method for preparing the electrochromic polymer film provided in this application has the following advantages:

[0010] (1) Traditional methods often use electropolymerization to prepare electrochromic polymer films, which requires a conductive substrate. This application uses in-situ oxidative polymerization, thus eliminating the need for a conductive substrate and enabling large-scale production. Furthermore, this method is compatible with industrial coating technologies (such as blade coating, slot coating, and roll-to-roll processing), making it more controllable, scalable, and efficient.

[0011] (2) The controllable range of film thickness is greater.

[0012] Since electrochromic polymer films generally lack conductivity, traditional electropolymerization methods cause the film to become an insulator after reaching a certain thickness, preventing further deposition and thickening. However, the preparation method used in this application employs direct coating with a coating solution, thus eliminating this limitation. This allows for a wider range of controllable polymer film thickness.

[0013] (3) The polymer film obtained by the above preparation method is also doped with highly reactive and strong counterions, such as perchlorate (ClO4). - (Ions). In the fabrication of electrochromic devices, there is no need to use electrolytes containing lithium salts, which reduces costs and avoids the use of potentially explosive chemicals.

[0014] (4) Lower cost and better compatible with existing industrial equipment

[0015] Traditional electropolymerization methods require large electrolytic cells filled with organic solvents for industrial-scale production. Electrochromic polymer films are then prepared one by one using a process similar to electroplating, resulting in high costs and energy consumption (therefore, no company currently uses this method for mass production of organic electrochromic polymer films). This method, however, allows for the direct use of existing industrial-grade printing and coating equipment to produce electrochromic polymer films, significantly reducing production costs. Attached Figure Description

[0016] Figure 1 illustrates the chemical formation mechanism of the polythiophene-based electrochromic polymer film in the preparation method of the electrochromic polymer film provided in this application.

[0017] Figure 2 shows the morphological characteristics of the electrochromic polymer film. Figure A illustrates the morphological characteristics of the electrochromic polymer film prepared using a secondary solvent in Example 1 of this application, with a substrate size of 400 mm. 2 Glass B shows the morphological characteristics of the electrochromic polymer film prepared without the use of secondary solvents in Example 1, with a substrate size of 400 mm. 2 The glass.

[0018] Figure 3 shows the morphology of the thin film prepared by the method in Example 1-1 of this application under an atomic force microscope.

[0019] Figure 4 shows the ultraviolet-visible-near-infrared transmittance of the electrochromic polymer film prepared in Example 5-1 of this application.

[0020] Figure 5 shows the ultraviolet-visible-near-infrared transmittance of the electrochromic polymer film prepared in Examples 5-2 of this application.

[0021] Figure 6 is a schematic diagram of a typical electrochromic device provided in this application.

[0022] Figure 7 shows the ultraviolet-visible-near-infrared transmittance of the electrochromic device prepared in Example 6-1 of this application.

[0023] Figure 8 shows the ultraviolet-visible-near-infrared transmittance of the electrochromic device prepared in Examples 6-2 of this application.

[0024] Figure 9 shows a comparison of the electrochromic device patterned by laser etching in Embodiment 6-1 of this application after applying a forward voltage and a reverse voltage, where A represents applying a forward voltage and B represents applying a reverse voltage.

[0025] Figure 10 shows a comparison of the electrochromic device patterned by laser etching in Embodiment 6-2 of this application after applying a forward voltage and a reverse voltage, where A represents applying a forward voltage and B represents applying a reverse voltage. Detailed Implementation

[0026] Unless otherwise stated, the terms used in this application have their common meanings as commonly understood by those skilled in the art. Unless otherwise stated, the values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (e.g., they can be tested according to the methods given in the embodiments of this application).

[0027] The list of items connected by the terms "at least one of," "at least one of," "at least one of," or other similar terms can mean any combination of the listed items. For example, if items A and B are listed, then the phrase "at least one of A and B" means only A; only B; or A and B. In another instance, if items A, B, and C are listed, then the phrase "at least one of A, B, and C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A may contain a single component or multiple components. Item B may contain a single component or multiple components. Item C may contain a single component or multiple components.

[0028] In view of the technical problems existing in the prior art, the first aspect of this application provides a method for preparing an electrochromic polymer film. The method includes: providing a precursor solution, wherein the precursor solution includes a main solvent, a secondary solvent, an oxidant, and a thiophene derivative monomer, wherein the secondary solvent is capable of forming a complex with at least some of the metal ions in the oxidant; coating the precursor solution onto a substrate surface, causing the thiophene derivative monomer to undergo an in-situ oxidative polymerization reaction to form an electrochromic polymer film, wherein the thiophene derivative monomer includes one or more of the following organic compounds:

[0029] The chemical formation mechanism of polythiophene electrochromic polymer films is shown in Figure 1.

[0030] Thiophene derivative monomers

[0031] Since the above preparation process is an in-situ oxidative polymerization reaction, the entire reaction is carried out in a solution environment. To improve the degree of reaction in the in-situ oxidative polymerization, the thiophene derivative monomer needs to have good solubility in the solvent. Compared to thiophene derivative monomers with other structures, the preparation method of the thiophene derivative monomer shown in the above structural formula is simple, and the electrochromic film obtained after polymerization has superior electrochromic properties. In some embodiments of this application, the thiophene derivative monomer includes, but is not limited to, at least one of 5,5'-(2,5-difluoro-1,4-phenylene)bis(2,3-dihydro[3,4-b]thiophene-1,4-dioxane), 2,2'-(2,5-difluoro-1,4-phenylene)dithiophene, and 3,6-bis(2,3-dihydro[3,4-b]thiophene-1,4-dioxane-5-yl)-9-methyl-9H-carbazole. Compared to other thiophene derivative monomers, the electrochromic polymer films prepared from the above-mentioned thiophene derivative monomers exhibit higher contrast before and after color change, wider operating voltage window, shorter response time, and better stability and lifespan.

[0032] In some embodiments of this application, the weight percentage of the thiophene derivative monomer in the precursor solution is 0.01–5 wt%. Optionally, the weight percentage of the thiophene derivative monomer in the precursor solution is 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, or a range formed by any two of the above values. Preferably, the weight percentage of the thiophene derivative monomer in the precursor solution is 0.2–0.8 wt%.

[0033] main solvent

[0034] The primary solvent is used to dissolve the thiophene derivative monomer, and therefore needs to be selected from solvents with high solubility for these non-polar, low-solubility organic compounds. In some embodiments of this application, the primary solvent includes at least one of chloroform, chlorobenzene, toluene, xylene, acetonitrile, and dimethyl sulfoxide. Compared to other solvents, the above-mentioned solvents have superior solubility for the thiophene derivative monomer, which is beneficial for improving the yield and thickness of the final electrochromic polymer film. In one embodiment, the primary solvent includes dimethyl sulfoxide (DMSO), which is beneficial for improving the density of the electrochromic polymer film.

[0035] In some embodiments of this application, the weight percentage of the main solvent in the precursor solution is 50-90 wt%. For example, the weight percentage of the main solvent is 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, or any range formed by the above values.

[0036] Oxidizing agent

[0037] Oxidizing agents are used to participate in in-situ oxidative polymerization reactions. In some embodiments of this application, the oxidizing agent includes at least one of Fe(ClO4)3, Fe(OTf)3, and Fe(OTs)3, preferably Fe(ClO4)3.

[0038] secondary solvents

[0039] In the oxidative polymerization reaction in the presence of Fe(III), the oxidant exhibits very strong reactivity in polar solvents, resulting in a short precursor solution lifespan and uneven in-situ oxidative polymerization film formation. To address this issue, the applicant introduced a secondary solvent into the preparation process of the electrochromic polymer film.

[0040] The main function of the secondary solvent is to react with at least some of the metal ions (such as Fe) in the oxidant. 3+ To slow down the oxidative polymerization reaction and achieve higher uniformity of the film, unstable complexes are formed. Therefore, solvents containing amide groups or P=O double bonds, such as cyclic amides, are preferred. In some embodiments of this application, the secondary solvent includes at least one of cyclic amides, chain amides, cyclic ureas, and chain alkyl ureas, preferably at least one of compounds of formula (A), (B), (C), (D), (E), and (F).

[0041] In formula (A), n is an integer from 1 to 8, and R is independently selected from C1-C8 alkyl groups, preferably C1-C8. 1- C6 alkyl, further preferably methyl, ethyl, propyl, butyl, pentyl or hexyl;

[0042] In formula (B), n is an integer from 0 to 8, and R is independently selected from C1-C8 alkyl, preferably C1-C6 alkyl, and more preferably methyl, ethyl, propyl, butyl, pentyl or hexyl;

[0043] In formula (C), R is independently selected from C1-C8 alkyl, preferably C1-C6 alkyl, and more preferably methyl, ethyl, propyl, butyl, pentyl or hexyl;

[0044] In formula (D), R is independently selected from C1-C8 alkyl, preferably C1-C6 alkyl, and more preferably methyl, ethyl, propyl, butyl, pentyl or hexyl;

[0045] In formula (E), R is independently selected from C1-C8 alkyl, preferably C1-C6 alkyl, and more preferably methyl, ethyl, propyl, butyl, pentyl or hexyl;

[0046] In formula (F), R is independently selected from C1-C8 alkyl, preferably C1-C6 alkyl, and more preferably methyl, ethyl, propyl, butyl, pentyl or hexyl.

[0047] In some embodiments of this application, the weight percentage of the secondary solvent in the precursor solution does not exceed 50 wt%, preferably 5 to 50 wt%. For example, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, or any range of the above values; more preferably 5 to 15 wt%.

[0048] By adjusting the type and amount of auxiliary solvents, the polymerization rate can be controlled, resulting in dense and uniform electrochromic polymer films. Furthermore, these auxiliary solvents can adjust the viscosity of the precursor solution, forming electrochromic polymer films of varying thicknesses (e.g., 20-1500 nm) and visible light transmittance. Control experiments show that using a solvent-free approach leads to excessively rapid reaction rates, causing polymer aggregation and shrinkage on the substrate, resulting in films with rough surfaces and even large pores (Figure 2).

[0049] Other components

[0050] In some embodiments of this application, the precursor solution further includes a polyethylene glycol copolymer. Adding the polyethylene glycol copolymer to the precursor solution can adjust its viscosity, thereby affecting the thickness and visible light transmittance of the final electrochromic polymer film. In some embodiments, the polyethylene glycol copolymer includes a polyethylene glycol-polypropylene glycol-polyethylene glycol triblock copolymer, and more preferably, the weight-average molecular weight of the polyethylene glycol-polypropylene glycol-polyethylene glycol triblock copolymer is 2900 to 14600. The weight-average molecular weight includes, but is not limited to, the above range, and limiting it within this range allows for adjustment of the thickness and visible light transmittance of the electrochromic polymer film within a wider range, increasing its market share. Furthermore, to ensure that the electrochromic polymer film has a suitable thickness and a suitable degree of polymerization, and to facilitate subsequent film cleaning steps, preferably, the weight-average molecular weight of the polyethylene glycol-polypropylene glycol-polyethylene glycol triblock copolymer is 2900 to 8400.

[0051] In some embodiments of this application, the weight percentage of the polyethylene glycol copolymer in the precursor solution is 2 to 6 wt%. For example, the weight percentage of the polyethylene glycol copolymer is 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, 5.5 wt%, 6 wt%, or any range of the above values.

[0052] In some embodiments of this application, the precursor solution further includes additives, preferably leveling agents. The addition of leveling agents helps improve the flowability and surface appearance of the precursor solution during the coating process, thereby enhancing the formation of a smooth, defect-free surface during drying or curing, and ultimately improving the performance of the final electrochromic polymer film.

[0053] In some embodiments of this application, after coating the precursor solution onto the substrate surface, the method for preparing the electrochromic polymer film further includes: post-processing the precursor solution on the substrate surface, wherein the post-processing step includes at least one of washing and drying.

[0054] In some embodiments, the reaction temperature of the in-situ oxidative polymerization reaction is 50–180°C. The reaction temperature of the in-situ oxidative polymerization reaction includes, but is not limited to, the above-mentioned range. Limiting it to this range is beneficial to improve the sufficiency of the in-situ oxidative polymerization reaction, thereby increasing the difference in visible light color change rate before and after color change. For example, the reaction temperature of the in-situ oxidative polymerization reaction is 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, or any range formed by the above values, preferably 80–180°C.

[0055] The polymerization time is adjusted according to the degree of polymerization reaction. Preferably, the polymerization time includes, but is not limited to, 0.1 to 20 minutes. For example, the polymerization time can be 0.1 min, 0.5 min, 1 min, 1.5 min, 2 min, 2.5 min, 3 min, 3.5 min, 4 min, 4.5 min, 5 min, 5.5 min, 6 min, 6.5 min, 7 min, 7.5 min, 8 min, 8.5 min, 9 min, 9.5 min, 10 min, 10.5 min, 11 min, 11.5 min, 12 min, 12.5 min, 13 min, 13.5 min, 14 min, 14.5 min, 15 min, 15.5 min, 16 min, 16.5 min, 17 min, 17.5 min, 18 min, 18.5 min, 19 min, 19.5 min, 20 minutes, or any range of the above values.

[0056] substrate

[0057] Since in-situ oxidative polymerization is not an electropolymerization process, the substrate does not need to be conductive. Therefore, in the above preparation method, the substrate can be conductive or non-conductive. In one embodiment, glass, ITO glass, or PET is used as the substrate.

[0058] Coating process

[0059] The method of coating the precursor solution onto the substrate surface can be a method commonly used in the art, such as spin coating, dip coating, slot die coating, or inkjet printing.

[0060] Unwanted components can be removed through the washing process. In some embodiments of this application, the product after polymerization is immersed in a solvent bath and washed with ethanol / methanol solvent to remove unreacted oxidants, inert copolymers and byproducts. The washed film is then dried (preferably at 50°C to 80°C) to obtain a uniform electrochromic polymer film.

[0061] A second aspect of this application also provides an electrochromic polymer film, which comprises an organic material represented by the following structural formula:

[0062] Wherein n is 1 to 5, and / or the above-mentioned electrochromic polymer film is prepared using the preparation method provided in this application. Optionally, the degree of polymerization n is 1, 2, 3, 4, 5 or any of the above values.

[0063] In some embodiments of this application, the thickness of the electrochromic polymer film ranges from 10 nm to 500 μm, and / or the operating voltage of the electrochromic polymer film is from -1.5 V to 1.5 V, and / or the maximum electrochromic contrast wavelength ranges before and after color change are 580 nm to 620 nm, 695 nm to 735 nm, and 405 nm to 445 nm, respectively, with a thickness of 10 nm to 500 μm. In some preferred embodiments, the maximum electrochromic contrast wavelength ranges before and after color change are 600 nm, 716 nm, and 423 nm, respectively, with a thickness of 10 nm to 500 μm.

[0064] A third aspect of this application also provides an electrochromic device, including an electrochromic layer comprising the electrochromic polymer film provided in this application. Preferably, the electrochromic device includes a membrane switch, electronic paper, electronic price tag, electrochromic display, smart window, or vehicle head-up display.

[0065] In some embodiments of this application, the color change range of the electrochromic device described above, expressed in the color coordinate system of the International Commission on Illumination (CIE) Lab table, is 6-1 (L=70, a=-4, b=15 to L=-49, a=-5, b=-24) and 6-2 (L=34, a=34, b=-17 to L=44, a=-11, b=-24).

[0066] The fourth aspect of this application also provides an application of the above-mentioned electrochromic polymer film in the field of electrochromism.

[0067] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0068] The equipment used in the embodiments and comparative examples, as well as the parameter calculation methods, are as follows:

[0069] Equipment and Methods: Coating: Prepared using a spin coater in a cleanroom. The glass has an average transmittance of 90% in the visible light range.

[0070] Ultraviolet-visible-near-infrared spectroscopy: Detection was performed using a Shimadzu UV-2600 UV-Vis spectrophotometer with a direct detector without an integrating sphere and a slit width of 5 nm.

[0071] Thickness: The thickness was measured using a KLA Alpha-Step D-600 probe profilometer. The profilometer was scratched three times, and the average value was taken to account for the thickness. The average deviation was then calculated.

[0072] Visible light transmittance: measured using a ColorSpectrum TH-100 haze meter.

[0073] The names and structures of representative secondary solvents used in this invention are shown in Table 1.

[0074] The names and structures of the representative thiophene derivative monomers used in this invention are shown in Table 2.

[0075] Table 1. Representative secondary solvents used in this invention

[0076] Table 2. Representative thiophene derivative monomers used in this invention

[0077]

Example 1

[0078] Example 1-1

[0079] The one-step preparation process of conductive polymer films is as follows:

[0080] The main solvent chloroform and the secondary solvent CLM were mixed in a certain proportion to form a solvent system. PEG-PPG-PEG (Mw = 8400) and the solid oxidant Fe(ClO4)3 were added to the solvent system and mixed thoroughly to form solution A. Solution A contained 87 wt% chloroform, 2 wt% CLM, 8 wt% PEG-PPG-PEG, and 3 wt% Fe(ClO4)3. Next, 10 mg of Cz-EDOT was added to 1.5 mL of solution A to form solution B. Solution B was then used at 400 mmHg for 5 min. 2 A film was spin-coated onto glass and annealed at 120°C for 5 min. Afterward, it was washed three times in an ethanol bath at room temperature for 10 min each time. Then, it was dried at 60°C for 30 min to obtain an electrochromic polymer film, the properties of which are shown in Table 3. The electrochromic process from color 1 (color when a forward voltage is applied) to color 2 (color when a reverse voltage is applied) was described using a 10... -5 The simulation was performed by treating the thin film with a mol / L hydrazine / ethanol solution. The specific steps were as follows: 10 mol / L hydrazine / ethanol solution was used... -5 A mol / L hydrazine / ethanol solution was added dropwise to the electrochromic polymer film in color 2 (the color when a reverse voltage is applied) until it was completely covered. Excess hydrazine / ethanol solution was then uniformly removed by spin coating. Heating the resulting sample to 60°C and drying for 5 minutes converted the electrochromic polymer film to color 1 (the color when a forward voltage is applied).

[0081] In Examples 1-2 to 1-8, we conducted experiments under the same test conditions as in Example 1-1, but with different auxiliary solvents (see Table 3).

[0082] Table 3. Effects of different auxiliary solvents on electrochromic polymer films

[0083] In this application, "visible light transmittance of colors 1 and 2" refers to the average transmittance in the visible light range (390-780nm).

[0084] Table 3 summarizes the average visible light transmittance and transmittance at the maximum color-changing wavelength (600 nm) of the films before and after color change at a specific film thickness. As shown in the table, the introduction of the auxiliary solvents listed in Table 1 can effectively control the reaction rate of in-situ oxidative polymerization, thereby improving the uniformity of the film. By adjusting the type of auxiliary solvent, the rate of the in-situ oxidative polymerization reaction can be controlled, thus obtaining films with different thicknesses and transmittance characteristics within the same reaction time.

[0085] Figure 2 shows a base size of 400 mm. 2The film morphology is shown in Figure 3. The figure shows that the film prepared with pure chloroform without the addition of a secondary solvent (B) exhibits oxidant crystal formation and an inhomogeneous film morphology. However, after adding the secondary solvents shown in Table 1, the film becomes uniform and highly ordered (A). Here, the secondary solvent adjusts the appropriate viscosity, polarity, and solubility to form a better film through electrostatic interactions with the oxidant and the PEG-PPG-PEG polymer. In this system, the PEG-PPG-PEG polymer guides polymer chain growth according to the systematic sequence used in gas-phase polymerization. Figure 3 shows the film morphology obtained by the method in Examples 1-1 under an atomic force microscope, with a roughness of only 2.38 nm and a very smooth and uniform surface.

[0086]

Example 2

[0087] Example 2-1

[0088] The main solvent chloroform and the secondary solvent CLM were mixed in a certain proportion to form a solvent system. PEG-PPG-PEG (Mw = 2900) and the solid oxidant Fe(ClO4)3 were added to the solvent system and mixed thoroughly to form solution A. Solution A contained 87 wt% chloroform, 2 wt% CLM, 8 wt% PEG-PPG-PEG, and 3 wt% Fe(ClO4)3. Next, 10 mg of Cz-EDOT was added to 1.5 mL of solution A to form solution B. Solution B was then used to incubate the solution at 400 mmHg for 5 minutes. 2 A film was spin-coated onto glass and annealed at 120°C for 5 min. Afterward, it was washed three times in an ethanol (or acetonitrile) bath at room temperature for 10 min each time. Then, it was dried at 60°C for 30 min to obtain an electrochromic polymer film, the properties of which are shown in Table 4. The electrochromic process from color 1 (color when a forward voltage is applied) to color 2 (color when a reverse voltage is applied) was described using a 10... -5 The thin film was treated with a mol / L hydrazine / ethanol solution for simulation.

[0089] In Examples 2-2 to 2-5, we conducted experiments under the same experimental conditions as in Example 2-1, replacing PEG-PPG-PEG with different molecular weights (see Table 4).

[0090] Table 4. Effect of using PEG-PPG-PEG with different molecular weights on the properties of electrochromic polymer films

[0091] Table 4 shows the properties of films obtained using PEG-PPG-PEG with different molecular weights. As can be seen from Table 4, with the increase of the molecular weight of PEG-PPG-PEG, the viscosity of solution B gradually increases, thus resulting in a gradual increase in the thickness of the final electrochromic polymer film. It should be noted that since PEG-PPG-PEG with Mw = 14600 is insoluble in ethanol, acetonitrile is required for cleaning.

[0092]

Example 3

[0093] Example 3-1

[0094] The main solvent chloroform and the secondary solvent CLM were mixed in a certain proportion to form a solvent system. PEG-PPG-PEG (Mw = 8400) and the solid oxidant Fe(ClO4)3 were added to the solvent system and mixed thoroughly to form solution A. Solution A contained 87 wt% chloroform, 2 wt% CLM, 8 wt% PEG-PPG-PEG, and 3 wt% Fe(ClO4)3. Next, 10 mg of Cz-EDOT was added to 1.5 mL of solution A to form solution B. Solution B was then used at 400 mmHg for 5 min. 2 A film was spin-coated onto glass and annealed at 60°C for 5 min. Afterward, it was washed three times in an ethanol bath at room temperature for 10 min each time. Then, it was dried at 60°C for 30 min to obtain an electrochromic polymer film, the properties of which are shown in Table 5. The electrochromic process from color 1 (color when a forward voltage is applied) to color 2 (color when a reverse voltage is applied) was described using a 10... -5 The thin film was treated with a mol / L hydrazine / ethanol solution for simulation.

[0095] In Examples 3-2 to 3-6, we performed annealing at 80-180°C using the same solution formulation as in Example 3-1 (see Table 5).

[0096] Table 5. Effect of annealing temperature on the properties of electrochromic polymer films

[0097] Table 5 shows the effect of annealing temperature on the properties of the electrochromic polymer film. As can be seen from Table 5, the effect of annealing temperature on film thickness is relatively small. At lower annealing temperatures (60℃), the transmittance of the electrochromic polymer film before and after color change is higher than at other temperatures, and the difference in transmittance before and after color change is smaller. This is because at lower temperatures, the polymerization reaction is less complete, resulting in a reduced film thickness and a smaller polymer molecular weight.

[0098]

Example 4

[0099] Example 4-1

[0100] The main solvent chloroform and the secondary solvent CLM were mixed in a certain proportion to form a solvent system. PEG-PPG-PEG (Mw = 8400) and the solid oxidant Fe(ClO4)3 were added to the solvent system and mixed thoroughly to form solution A. Solution A contained 87 wt% chloroform, 2 wt% CLM, 8 wt% PEG-PPG-PEG, and 3 wt% Fe(ClO4)3. Next, 10 mg of Cz-EDOT was added to 1.5 mL of solution A to form solution B. Solution B was then used at 400 mmHg for 5 min. 2 A film was spin-coated onto glass and annealed at 120°C for 5 min. Afterward, it was washed three times in an ethanol bath at room temperature for 10 min each time. Then, it was dried at 60°C for 30 min to obtain an electrochromic polymer film, the properties of which are shown in Table 6. The electrochromic process from color 1 (color when a forward voltage is applied) to color 2 (color when a reverse voltage is applied) was described using a 10... -5 The thin film was treated with a mol / L hydrazine / ethanol solution for simulation.

[0101] In Examples 4-2 to 4-4, we conducted experiments under the same experimental conditions as in Example 4-1, replacing different main solvents (see Table 6).

[0102] Table 6. Effect of the main solvent on the properties of electrochromic polymer films

[0103] Table 6 shows the effect of changing the main solvent on the properties of the electrochromic polymer film. As can be seen from Table 6, this in-situ polymerization method is adaptable to a variety of solvents. The films obtained from chloroform and chlorobenzene show very similar properties. DMSO, due to its high boiling point and ability to reduce the rate of oxidative polymerization, produces a denser and thinner film. Acetonitrile, due to its poor solubility for Cz-EDOT, also yields an electrochromic polymer film with a relatively short thickness.

[0104]

Example 5

[0105] Example 5-1

[0106] The main solvent chloroform and the secondary solvent CLM were mixed in a certain proportion to form a solvent system. PEG-PPG-PEG (Mw = 8400) and the solid oxidant Fe(ClO4)3 were added to the solvent system and mixed thoroughly to form solution A. Solution A contained 87 wt% chloroform, 2 wt% CLM, 8 wt% PEG-PPG-PEG, and 3 wt% Fe(ClO4)3. Next, 10 mg of Cz-EDOT was added to 1.5 mL of solution A to form solution B. Solution B was then used at 400 mmHg for 5 min. 2A film was spin-coated onto glass and annealed at 120°C for 5 min. Afterward, it was washed three times in an ethanol bath at room temperature for 10 min each time. Then, it was dried at 60°C for 30 min to obtain an electrochromic polymer film, the properties of which are shown in Table 6. The electrochromic process from color 1 (color when a forward voltage is applied) to color 2 (color when a reverse voltage is applied) was described using a 10... -5 The thin film was treated with a mol / L hydrazine / ethanol solution for simulation.

[0107] In Examples 5-2 and 5-3, we conducted experiments using F-EDOT and F-thiophene as monomers under the same experimental conditions as in Example 5-1 (see Table 7).

[0108] Table 7. Properties of electrochromic polymer films made using different thiophene derivative monomers

[0109] Table 7 shows the properties of electrochromic polymer films prepared using three different thiophene derivative monomers, with a degree of polymerization (n) ranging from 1 to 3. As can be seen from Table 7, this solution system and preparation process are applicable to one-step polymerization-coating of thiophene derivative electrochromic polymer films, exhibiting excellent substrate compatibility and versatility. Figures 4 and 5 show the UV-Vis-NIR absorption spectra of the electrochromic polymer films prepared in Examples 5-1 and 5-2, respectively, in color 1 (color when a forward voltage is applied) and color 2 (color when a reverse voltage is applied).

[0110]

Example 6

[0111] Example 6-1

[0112] The solution from Example 5-1 was applied to a 1600 mm thick surface within 5 minutes of preparation. 2 The film was deposited on ITO glass and annealed at 120°C for 5 min. Then, it was washed three times in an ethanol bath at room temperature for 10 min each time. Finally, it was dried at 60°C for 30 min to obtain an electrochromic polymer film uniformly adhered to a transparent electrode.

[0113] The ion storage layer (neutral PEDOT) attached to the transparent electrode was prepared by slightly modifying a method previously published in the literature (DOI:10.1021 / acs.chemmater.6b01035).

[0114] A UV-curable electrolyte was coated onto an electrochromic polymer film, followed by the ion storage layer, and air bubbles were removed. The electrolyte was cured by UV irradiation for 3 minutes, resulting in an electrochromic device with the structure of glass / ITO electrode / electrochromic polymer film / electrolyte / ion storage layer / ITO electrode / glass. The performance parameters of the electrochromic device are shown in Table 7.

[0115] In Example 6-2, we conducted experiments using the solutions from Example 5-2 under the same experimental conditions as in Example 6-1 (see Table 8).

[0116] Figure 6 is a schematic diagram of the electrochromic device. Figures 7 and 8 show the UV-Vis-NIR absorption spectra of the electrochromic polymer films prepared in Examples 6-1 and 6-2, respectively, in color 1 (color when a forward voltage is applied) and color 2 (color when a reverse voltage is applied). Figures 9 and 10 show examples of electrochromic devices after laser etching patterns. The color change range of the electrochromic device, expressed using the CIE Lab color system coordinates, is as follows: 6-1 (L = 70, a = -4, b = 15 to L = -49, a = -5, b = -24) and 6-2 (L = 34, a = 34, b = -17 to L = 44, a = -11, b = -24).

[0117] Table 8. Characteristics of the electrochromic device made from the electrochromic polymer film of Example 5

[0118] While some exemplary embodiments of this application have been described and illustrated, this application is not limited to the disclosed embodiments. Rather, those skilled in the art will recognize that modifications and changes may be made to the described embodiments without departing from the spirit and scope of this application as described in the appended claims.

Claims

1. A method for preparing an electrochromic polymer film, characterized in that, The method for preparing the electrochromic polymer film includes: A precursor solution is provided, wherein the precursor solution comprises a main solvent, a secondary solvent, an oxidant, and a thiophene derivative monomer, wherein the main solvent and the secondary solvent are different, and the secondary solvent is capable of forming a complex with at least some of the metal ions in the oxidant; The precursor solution is coated onto the substrate surface, causing the thiophene derivative monomer to undergo in-situ oxidative polymerization to form an electrochromic polymer film, wherein the thiophene derivative monomer includes one or more of the following organic compounds:

2. The method for preparing the electrochromic polymer film according to claim 1, characterized in that, The thiophene derivative monomers include at least one of 5,5'-(2,5-difluoro-1,4-phenylene)bis(2,3-dihydro[3,4-b]thiophene-1,4-dioxane), 2,2'-(2,5-difluoro-1,4-phenylene)dithiophene, and 3,6-bis(2,3-dihydro[3,4-b]thiophene-1,4-dioxane-5-yl)-9-methyl-9H-carbazole.

3. The method for preparing the electrochromic polymer film according to claim 1, characterized in that, The method for preparing the electrochromic polymer film includes any one of the following conditions: (1) The reaction temperature of the in-situ oxidative polymerization reaction is 50–180 °C; (2) The reaction time of the in-situ oxidative polymerization reaction is 0.1 to 20 min; (3) The main solvent includes at least one of chloroform, chlorobenzene, toluene, xylene, acetonitrile and dimethyl sulfoxide; (4) The secondary solvent includes at least one of cyclic amides, chain amides, cyclic ureas, and chain alkyl ureas; (5) The oxidant includes at least one of Fe(ClO4)3, Fe(OTf)3 and Fe(OTs)3.

4. The method for preparing the electrochromic polymer film according to claim 3, characterized in that, When the preparation method of the electrochromic polymer film includes condition (4), the secondary solvent includes at least one of the following: compound (A), compound (B), compound (C), compound (D), compound (E), and compound (F). In formula (A), n is an integer from 1 to 8, and R is independently selected from C1-C8 alkyl groups; In formula (B), n is an integer from 0 to 8, and R is independently selected from C1-C8 alkyl groups; In formula (C), R is independently selected from C1-C8 alkyl groups; In formula (D), R is independently selected from C1-C8 alkyl groups; In formula (E), R is independently selected from C1-C8 alkyl groups; In formula (F), R is independently selected from C1-C8 alkyl groups.

5. The method for preparing the electrochromic polymer film according to any one of claims 1 to 4, characterized in that, The precursor solution further includes a polyethylene glycol copolymer, which includes a polyethylene glycol-polypropylene glycol-polyethylene glycol triblock copolymer with a mass-average molecular weight of 2900 to 14600.

6. The method for preparing the electrochromic polymer film according to claim 5, characterized in that, The polyethylene glycol copolymer includes a polyethylene glycol-polypropylene glycol-polyethylene glycol triblock copolymer with a mass-average molecular weight of 2900 to 8400.

7. The method for preparing the electrochromic polymer film according to claim 5, characterized in that, The precursor solution satisfies any one of the following conditions: (1) In the precursor solution, the weight percentage of the thiophene derivative monomer is 0.01 to 5 wt%; (2) In the precursor solution, the main solvent has a weight percentage of 50-90 wt%; (3) In the precursor solution, the weight percentage of the secondary solvent does not exceed 50 wt%; (4) In the precursor solution, the weight percentage of the polyethylene glycol copolymer is 2 to 6 wt%; (5) The precursor solution also includes additives.

8. The method for preparing the electrochromic polymer film according to claim 7, wherein when the precursor solution meets condition (1), the weight percentage of the thiophene derivative monomer in the precursor solution is 0.2 to 0.8 wt%. When the precursor solution meets condition (3), the weight percentage of the secondary solvent in the precursor solution is 5 to 50 wt%. When the precursor solution meets condition (5), the additives include leveling agents.

9. The method for preparing the electrochromic polymer film according to any one of claims 1 to 4, characterized in that, After coating the precursor solution onto the substrate surface, the method for preparing the electrochromic polymer film further includes: The precursor solution on the substrate surface is post-treated, and the post-treatment steps include at least one of washing and drying.

10. The method for preparing the electrochromic polymer film according to claim 1, characterized in that, The It is 2,5-difluoro-1,4-phenylene or 9-methyl-9H-3,6-carbazole.

11. An electrochromic polymer film, characterized in that, The electrochromic polymer film comprises organic materials represented by the following structural formula: Wherein n is 1 to 5, and / or the electrochromic polymer film is prepared by any one of claims 1 to 10.

12. The electrochromic polymer film according to claim 11, characterized in that, The thickness of the electrochromic polymer film ranges from 10 nm to 500 μm, and / or the operating voltage of the electrochromic polymer film is from -1.5 V to 1.5 V, and / or the maximum electrochromic contrast wavelength ranges of the electrochromic polymer film before and after color change are 580 nm to 620 nm, 695 nm to 735 nm, and 405 nm to 445 nm, respectively.

13. The electrochromic polymer film according to claim 11, characterized in that, The It is 2,5-difluoro-1,4-phenylene or 9-methyl-9H-3,6-carbazole.

14. An electrochromic device, comprising an electrochromic layer, characterized in that, The electrochromic layer comprises the electrochromic polymer film according to any one of claims 11 to 13.

15. The electrochromic device according to claim 14, characterized in that, The electrochromic device exhibits a transmittance variation of not less than 25% in the wavelength range of 590nm to 630nm and a transmittance variation of not less than 10% in the wavelength range of 390nm to 450nm; or the electrochromic device exhibits a transmittance variation of not less than 20% in the wavelength range of 540nm to 560nm and a transmittance variation of not less than 30% in the wavelength range of 660nm to 740nm.

16. The electrochromic device according to claim 14, characterized in that, The electrochromic devices include membrane switches, electronic paper, electronic price tags, electrochromic displays, smart windows, or vehicle head-up displays.

17. The application of the electrochromic polymer film of claim 11 or 12 in the field of electrochromism.

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